This invention relates to an improvement in semi-aqueous stripping compositions particularly useful for stripping photoresists, photoresist residues, and other residues from silicon wafers.
During manufacture of semiconductors and semiconductor microcircuits, it is frequently necessary to coat the substrates from which the semiconductors and microcircuits are manufactured with a polymeric organic film, generally referred to as a photoresist, e.g., a substance which forms an etch resist upon exposure to light. These photoresists are used to protect selected areas of the surface of the substrate, while the etchant selectively attacks the unprotected area of the substrate. The substrate is typically a silicon dioxide coated silicon wafer and may also contain metallic microcircuitry, such as aluminum, copper, tungsten, titanium, tantalum, and metal alloys and nitrides, on the surface. Following completion of the etching operation and washing away of the residual etchant, it is necessary that the resist be removed from the protective surface to permit essential finishing operations. It is desirable to develop an improved stripping and cleaning composition to remove the organic polymeric substrate from a coated inorganic substrate without corroding, dissolving or dulling the metal circuitry and without removing the silicon wafer material either. The silicon wafer may be exposed to the photoresist stripping and cleaning composition (also referred to herein as “stripper” or “cleaning composition” or “stripping and cleaning composition”) during the application of the first layers of circuitry onto the front side of the wafer, where grippers are used to handle the wafer, and on the backside of the wafer. Typically the exposed portions of the silicon wafer are passive to stripping cleaning compositions. However, in some cases, the exposed silicon may get etched by photoresist strippers, particularly high pH strippers. These strippers may contain amines, quaternary bases, and mixtures thereof. It is therefore desirable to provide an improved stripper that does not etch the silicon wafer and instead, provides improved silicon passivation.